This option allows to select a page, which settings will be duplicated by Archive, Search, etc. pages.
For example, you have “My Sample” page with page title aligned to the right and sidebar on the left. If you select this page in Theme Options -> Archives -> Archives, it means that all Archive pages will also have page title on the right and sidebar on the left.

Content layout (beta feature V 6.4.0)

Archives content and Search results appearance will be rendered in accordance with first corresponding shortcode found on the page. Otherwise it will default to a masonry layout. So you need to insert a VC Blog element to the page and configure it. Categorization is always disabled and pagination defaults to a ‘standard’ mode. content layout will not change when using blog templates.